1. Field of the Invention
This invention relates generally to that class of inventions which includes patient implantable prosthetic devices which offer therapeutic benefits to such patients. More specifically, this invention relates to an implantable, patient-actuated, pump.
2. Description of Prior Art
In the broad field of implantable prosthetic devices, one might encounter a wide spectrum of technology ranging from implantable demand heart pacemakers to implanted artificial hip sockets. However, the prior art for the present invention falls within a narrower category of technology relating to implantable pumps.
Companies are today offering implantable pumps in the market place. One particular company offers an expensive pump system that incorporates complicated mechanism: a pump motor, microelectronics, lithium batteries, external (hand-held) programming devices, etc. The programming devices incorporate radio-frequency transmission to control the pump. While this pump might be attractive as a research device, the cost and complexity of this pump preclude its general therapeutic use.
Another pump available to the marketplace today consists of two chambers separated by a flexible metal bellows: one chamber acts as a drug reservoir, while the other is the sealed power supply containing a two-phase charging fluid in equilibrium. Working with vapor pressures, condensations to the liquid state, etc., this system eliminated need for batteries. But, the fluid is again pumped to certain patient locations without any control by the patient and is inherently unresponsive to changing patient needs.
The kinds of therapeutic applications undertaken by these pumping schemes are many. They include application of nitroglycerine for coronary vascular spasm, application of theophyeline for asthma, application of antineoplastic agents (chemotherapy) for cancer, application of lidocaine for cardiac arrythmia, application of antimicrobial and antiviral agents for chronic infection (e.g. osteomyelitis), application of morphine and other opiates, endorphines, substance P for chronic intractable pain, and many other applications of other substances/drugs for other medical maladies. In many, if not all of these instances, an improvement would be achieved if the application were made when the patient sensed the need for the substance, and then controlled the application of the substance.
There is a large market for these pump devices. In the United States alone, with respect to the subject of cancer chemotherapy, there are 850,000 new cases per year; there are 1.8 million persons suffering chronic or intractable pain; and 0.5 million new cases per year needing chronic antibiotic therapy. All of these human beings would benefit from drug substances that could be pin-point applied to the area of need, and only when needed.
It is thus understood that there are shortcomings in the prior art: this therapy may be provided at varying rates, and programmable rates, but never in direct response to patient needs, as sensed by the patient. Applicant has seized upon a solution to this shortcoming, and to implantable pump shortcomings associated with complicated technology, and discloses and claims herein a significant advance in the art of implantable pumps.